This paper describes the comprehensive morphological characteristics of ten Mastogloia Thwaites ex W. Smith (Bacillariophyceae) species, including, M. aquilegiae, M. baldjikiana, M. binotata, M. grunowii, M. ignorata, M. paradoxa, M. pumila, M. cf. regula, M. similis and M. vasta. Specimens were examined under the light microscope; eight of them are reported for the first time from Turkish coastal waters. Apart from the photo documentation, some information on the species geographical distribution patterns and the type of the substratum are also provided.